Caedarai

MC and VISA are the networks. They allow communication between banks, and the entire operation is packaged up by payment processors like Stripe, Square or PayPal. So you have processors, the banks on either end (perhaps two separate ones), the network operator, and additionally any extra companies that might offer additional services for the transaction, like for fraud prevention or financing.

That’s actually the version that’s in the AUR, since they can’t put newer (fixed) code in there from the new versions.